Electric cut-out



Aug. 3 1926.

J. VALERUS ELECTRIC GUT-OUT Filed 001'.. 12. 1925 Patented Aug. 3,.1926.

UNITED STATES 1,595,061 PATENT OFFICE.

JOHANN VALEBIUB, OF BRESLAU, GERMANY.

ELEUIBIC CUT-OUT.

Application lled October 12, 1923, Serial No. 668,157, and in GermanyOctober 17, 1922.y

crease of the current, whereby the circuit is interrupted. The electriccut-out according to the invention differs from the electric cut-outs ofknown type in that a metal body having capillary connecting channels ismounted between the capillary bore of the insertion, which consists ofhighly refractory incombustible insulating material and is designed toreceive the mercury thread, and the outflow orifice of the reservoir forthe liquid metal. In this manner liquid metal 1s prevented from flowinaccidentally from the reservoir through t e capillary bores of theinsertion or from being drawn along from the reservoir when the liquidmetal at the capillary point vaporizes.

The invention twill be best understood from a consideration of thefollowing detailed description taken in connection with the accompan ingdrawing forming a part of this speci cation, with the understanding thatwhile on the drawings one embodiment of the invention is disclosed, theinvention is not confined to any strict conformity with the showing ofthe drawings, but may be embodied in any manner which does not make amaterial departure from the salient features of the invention.

In the drawings zv Fig. 1 shows in longitudinal section the preferredform of construction of the im-` proved electric cut-out.

Fig. 2 shows in longitudinal section yon enlarged scale a modificationof the cut-out shown in Fig. 1.

Fig. 3 shows in frontelevation the front end of the cut-out shown inFig. 1.

In the insulating body 1 an exchangeable insertion 2 of highlyrefractory incombustible insulating material is located which has acapillary bore 3 enlarged towards both ends. The lower end of theinsertion 2 encloses a small metal cylinder 4 having a narrow bore 5 andit rests u on a cross partition 8 of the insulating body 1. The crosspartition 8 has a bore 7 and a perforated packing disk 6 is insertedbetween 2 and 8. The 'insertion is pressed by means of a metal screw 10upon the packing disk 6 or the cross partition 8. This metal screw 10has a central bore 9 and it is screwed into an internally threaded metaltube 12 inserted in a hollow space 11 of the insulating body 1 above theinsertion 2. A metal lid 13 is screwed into the upper end of tube 12 andsecuredv against removal in any convenent manner not shown in thedrawing. A movable rod 15 having a disk 14 at its lower end and knob 16at the upper end traverses the lid 13. The upper yend 17 of screw 10 isof shorter diameter than the remainder of the screw so that around thepart 17 an annular space 18 is formed in the metal tube 12. Between thefoot end of screw 10 and the insertion 2 a perforated packing disk 19 isinserted.

In the hollow space 20 in the insulating body 1 below the crosspartition 8 a cup shaped'metal body 21 is inserted. A screw 23 having ahead 22which serves as handle and carrying at its upper end a pistonfitting into the cup is screwed into the bottom of the cup 21. Thepiston 25 is secured against removal from the insulating body or fromthe cup.

After the lid 13 has been removed and after the screw 10 has beenscrewed out the space 24 above the piston 25 is filled with mercury inthefactory where the cut-outs are made. The mercury is poured in throughthe bores 9, 3 and 7 `whereupon with the aid of the screw 23, the head22 of which is turned, the piston 25 is raised until the mercury hasraised in the bore 9 up tothe point 26. The meta-l cup 21 is nowelectrically connected with the metal lid 13 by a mercury thread.

The foot plate 14 of rod 15 rests upon the upper edge of the thin part17 of screw 10. The lid is screwed on and the device is ready fortransport and for use when the lid 13 has been secured against gettingloose.

For use the cut-out is inserted in the circuit, for instance between thenut and screw of a plug contact so that on the one hand the metal cup 21and on the other hand the metal lid 13 are supplied with current. Thecut-out is generally in horizontal position and not in vertical positionas shown in the drawing. y

When the current increases excessively the mercury begins to vaporize atthe narrowest point of the capillary bore 3 whereby the mercury threadabove the capillary point is thrown, in displacing the rod 15 in thebore 9 of the screw 10, into the annular space 18 surrounding the thinpart 17 of the screw 10. The mercury collects in this space 18 and thecircuit is interrupted between the two contacts 20, 13. The cutout beingin horizontal position the rod 15 remains in this new position andindicates thus the interruption of the current.

To bring the cut-out back to the normal state it is turned approximatelyto a vertical position so that the rod 15 drops upon the upper edge ofthe thin extension 17 of screw 10. The screw 23 is screwed up until themercury displaced by the piston 25 has risen in the bore 9 of screw 10and begins to lift rod 15. At this instant the screwing in of screw 23is stopped or the screw is even slightly screwed back so that themercury level stands approximately at the point 26. The mercury levelmust always stand somewhat below the upper edge of bore 9 so that themercury does not flow over into the annular space 18 when it begins tobe heated by the current which flows through; the chamber 24 is of sucha size that the quantity of mercury stored in the same is suiicient fora determined number of short-circuits. At each short-circuit the innerwidth of the capillary bore 3 is enlarged in a very slight measure buteven after the determined number of short-circuits this inner width isstill so narrow that the cut-out could serve :for further shortcircuits.As however the enlargements of the inner width of the capillary bore 3is uncertain it is advisable to prevent the recharging of the cut-outwith mercury by any unauthorized person. With this object in view thelid 13 is locked so that it cannot be screwed out of tube 12 and so thatspace 24 is not accessible. If the capillary bore 3 should have beenwidened excessively the insertion 2 could be exchanged in the factoryagainst a new one. The expenses are evidently much lower than in thecase that the'capillary bore is arranged directly in the insulating bodyso that this insulating body would have to be exchanged entirely or forits most essential parts. The fine bore 5 in the metal body 4 serves toprevent that accidentally, during transportation of the cut-out, mercuryflows over from the space 24 into the bore 9 and from there into theannular space 18. This object is attained in even a more thorough mannerwhen the fine bore 5 of the metal body 4 between the bores 7 and 3 doesnot extend straight but is undulated or in zig-zag. IA still bettereffect is obtained if for the metal body 4 a hollow metal body 4'L (Fig.2) is substituted in which an asbestos stopper 27 is arranged which letsthe mercury pass only at a determined ressure which occurs also at theturning o? the screw. This asbestos stopper prevents with greatersecurity than the metal body 4 ("Fig. l) that at the vaporizing of themercury in the capillary bore 3 any mercury be drawn along from thereservoir to be projected through the bore 9 of the screw 10 into theannular space 18. Notwithstanding the use of a metal body with capillaryconnecting channels between the capillary bore 3 of the insertion 2 andthe non-capillary outflow openings 7 of the store space 24 the danger ofshort-circuits in these connectingr channels is excluded, as the totalcross section of t-he metal body is still suiiicient for the passage ofthe excessively increased current.

As the space 24 is not influenced by the vapor-ization of the mercury inthe capillary bore 3 the quantity of mercury in space 24 will not varyeven at short-circuits. This is important for there-establishment of thecut-out as for each rcs-establishment a rotation of the screw 23 for oneand the same predetermined angle is required. A scale 28 (Fig. 3) on theouter surface of the insulating body 1 and a hand 29 on the screw aretherefore arranged to indicate the quantity of mercury in space 24. Thescale may however be on the screw and the hand on the insulating body oron the metal cup 21.

I claim y 1. An electric cut-out comprising in combination an insulatingbody, two metal contacts embedded in said insulating body, a thread ofliquid metal narrowed to a capillary point in said insulating body andconnecting said metal contacts, an insertion of highly refractoryinsulating material having a capillary bore for said thread of liquidmetal, a reservoir for the liquid metal having an outflow orifice, and ametal body having a capillary channel inserted between said outfioworifice of the reservoir and said capillary bore of the insertion.

2. An electric cut-out comprising in combination an insulating body, twometal contacts embedded in said insulating body, a thread of liquidmetal narrowed to a capillary point in said insulating body andconneeting said metal contacts, an insertion of highly refractoryinsulating material having a capillary bore for said thread of liquidmetal, a reservoir for the liquid metal having an outflow orifice, and ametal body having a capillary channel inserted between said outfloworifice of the reservoir and said capillary bore of the insertion, and atubular pressure screw acting upon the end of the insertion opposite thesaid metal body for pressing said insertion against said metal body andsaid metal body against the outflow orifice of said reservoir.

3. An electric cut-out comprising in combination an insulating body, twometal contacts embedded in said insulating body, a thread of liquidmetal narrowed to a capilessing sai lary -point in said insulating bodyand connecting said metal contacts, an insertion of highly refractoryinsulating material having a capillary bore for said thread of liquidmetal, a reservoir for the liquid metal having an outflow orifice, and ametal body having a capillary channel inserted between said outfloworifice of the reservoir and said capillary bore of the insertion, atubular pressure screw acting'upon the end of the insertion opgosite thesaid metal body for insertion against said metal dy and said metal bodyagainst the outflow orifice of said reservoir and a thin extension onthe inner end of said tubular pressure screw so that an annular spa isformed around this extension which is designed to collect the liquidmetal forced through the bore of the screw when a shortcircuit occurs.

4. An electric cut-out comprising in combination an insulating body, twometal contacts embedded in said insulating body, a thread of liquidmetal narrowed. to a capillary point in said insulating body andconnecting said metal contacts, an insertion of -highly refractoryinsulating material having a capillary bore for said thread of liquidmetal, a reservoir for the liqud metal having an outflow orifice, and ametal body having a capillary channel inserted between said outfloworifice of the reservoir and said capillarybore of'the insertion, atubular pressure screw acting upon the end of the insertion oposite thesaid metal body for grossing-sai insertion against said metal ody andsaid metal body against the outflow orifice of said reservoir and a thinextension on the inner end of said tubular pressure screw so that anannular space is formed around this extension which is designed tocollect the liquid metal forced ture.

JOHANN VALERIUS.

